There's supposedly some neurological studies out there about the origins of transness, but they're not very good:
Most of them have small sample sizes
They often involve brain parts that are not very well understood, and brain properties that are not very well understood
AFAIK neurology is just not that good of a field yet
Neurology should in principle be able to completely settle what causes transness. But what are the commonly proposed causes? Here's two theories that I've seen discussed a lot:
Feminine essence: Some sort of "identity essence" in the brain, such as a neurological body map, can be either male or female, and trans women are males who have been born with a female version of this essence.
Blanchardian: Among gynephilic trans women, the primary cause is autogynephilia, a sexual attraction to being a woman, whereas among androphilic trans women, the cause is unknown, probably similar to the feminine essence but more malleable than the feminine essence model would suggest.
Beyond these two, I also want to introduce three other theories that can be considered plausible:
Neither: Something else, e.g. massive polycausality, explains trans women, and the previously mentioned factors are either epiphenomena or only account for a small fraction of trans women.
Feminine autogynephilia: Similar to the feminine essence theory, there is a part of the brain that is feminized and causes a feminine gender identity. But the important part of the brain is specifically a part of one's sexuality, and the same aspect of sexuality that e.g. autogynephilic cis men have, so the theory doesn't entirely differ from the Blanchardian model either.
Just autogynephilia: Like in the Blanchardian model and unlike in the feminine autogynephilia model, autogynephilia is the major cause of transsexuality among gynephilic trans women. But unlike the Blanchardian model, it is also the major cause of transsexuality among androphilic trans women.
If a good neurological study is performed that proves one of these theories, then the market will resolve to the corresponding theory. If a very good genetic study or other study proves one of these theories, and people stop investigating it neurologically for some reason, then the market will resolve to the corresponding theory. If no theory gets proven then the market doesn't resolve. If it becomes unresolvable (e.g. all of humanity gets uploaded to computers through some means that doesn't preserve information about how transsexuality works) then the market resolves N/A.
If repression or social contagion (ROGD) plays a role, then repression or social contagion will not be counted, and we will instead consider the other factors residual for repression or social contagion.
I won't be trading in this market.
Related questions
New study on a subject adjacent to autogynephilia: Elaborating and Testing Erotic Target Identity Inversion Theory in Three Paraphilic Samples
@Sinclair Depends on how it is caused by the physical environment.
If it's something that interferes with masculinization or causes some sort of feminization, then it will almost certainly resolve to feminine essence.
However otherwise (e.g. if the physical factor has nothing to do with sex hormones) it might resolve to some other theory.
@tailcalled I should note that it will only "almost certainly" resolve to feminine essence if the hormonally interference is the main factor, not if it is one out of many.
Like if there's a normally distributed continuum of biological femininity, and this is one of the contributors to transition, but trans women are only 1 within-sex standard deviation higher than cis men in this continuum, then the market will probably not resolve to feminine essence (but might likely resolve to neither), despite the fact that 1 standard deviation is big compared to the effect sizes you typically see in social science.
This is because if it was the sole cause of transition, we'd expect trans women to be like 2-4 standard deviations above average (depending on the estimated transition rate), and if it was a primary-but-not-sole-cause you'd still expect trans women to be pretty close to that.
Disclaimer: I may have some of the math wrong here because I'm just going off the top of my head. I'll make sure to post my reasoning for discussion and critique before resolving the market. Though once we know enough to resolve the market, I don't expect we'll need to apply this sort of argument bwcause we understand the mechanisms in more detail.
There's been some discussion of the resolution criteria in various places, so I should probably write the conclusions here too:
If transness is caused by body dysmorphic disorder, then this market probably resolves Neither (unless e.g. body dysmorphic disorder turns out to have to do with a feminine essence in which case it resolves Feminine essence)
If transness is caused by autism then this market probably resolves Neither (unless e.g. the people who argue that autism is a form of unmasculinity are right, in which case it probably resolves Feminine essence, or unless the people who argue that autism is a form of hypermasculinity associated with autogynephilia are right, in which case it may resolve to some of the autogynephilia theories)
I don't think any of the above resolutions are very likely though, just based on statistics and propertues of the things in question.
(AFAIK a defining feature of BDD is that changing your body won't help with it, so that seems to contradict it being a trans thing. While transness may be somewhat correlated with autism, I think the correlation is too weak for the market to resolve with autism as a major fact. Also both the unmasculinity and the hypermasculinity theories of autism seem too weak to me. But sure, if the evidence changes then I will change my mind with it.)
If there's differences between gynephilic and androphilic trans women, with gynephilic trans women being later transitioning, more masculine in their childhood, more likely to be behaviorally fetishistic, etc. (so some of the patterns described by Blanchardians hold up), but gynephilic and androphilic trans women transition due to the same causes and the differences just turn out to be epiphenomena (e.g. it's well-known that sexual orientation correlates with masculinity/femininity), then this question does not resolve to "Blanchardian" because I consider the causal claims to be a defining feature of Blanchardianism. Instead it may resolve to any of the other options depending on the exact details of what causes it.
If neurologists go in and find that this question is totally intractable neurologically because Feminine essence theory and Autogynephilia-based theories assume that transness is to do with these very specific sorts of causes, but really transness has all sorts of random bizarre causes that aren't compressible to a human-understandable theory, then this market will likely resolve to Neither. Unless it is found that Autogynephilia/Feminine essences are due to processes that are very neurologically opaque (e.g. childhood socialization), in which case non-neurological studies may turn out to prove one of the theories in the market.
If Autogynephilia turns out to play only a minor role, e.g. accounting for 10% of trans women's motivation to transition, then the market would not resolve to an Autogynephilia-based theory. Yes I know that in social science such an effect size would often be considered unreasonably big, but that is because social scientists are bad at their job. Think about the effect sizes of the residual; if Autogynephilia accounted for 10% of the motivation then that would mean that non-Autogynephilia factors account for 90% of the motivation, and then obviously it would be inaccurate to summarize this as being due to Autogyneohilia while ignoring the other factors.
Seems interesting how "neither" has 4x more probability than "feminine essence" considering the debate is usually between "feminine essence" and "Blanchardianism".
Not necessarily a wrong conclusion (I would be prone to agreeing that too much weight is put on feminine essence, though I also think this market is underrating feminine AGP/just AGP compared to Blanchardianism), but interesting.
@IanC The phrasing "wanted to" makes it sound like you are trying to suppress autogynephilia theories, rather than genuinely believing them to be unlikely. Which is fair enough; it's a free market.
However, I notice that I am confused, because if you announce that you are trying to suppress their probabilities, then other market participants will hear your announcement and learn that the market is biased. And this makes it an obvious target for extracting profit, as they can then in expectation earn mana by bidding up the autogynephilia theories. (This is part of the beauty in prediction markets, that they should - at least in theory - be resistant to manipulation.)
Not sure if you didn't realize this dynamic, or didn't actually mean that you were trying to suppress the autogynephilia theories, or are okay with the dynamic anyway, or something else.
@tailcalled My comment was pretty hastily written and I can definitely see how my comment suggests this as my intention.
I didn't mean to be suppressing them or making them go down in some sort of "contest" way. Rather, I saw all the options at 20% and thought that, based on my priors, the autogynephilic theories together are less than 60% likely to be true. I haven't done enough research to prefer feminine essence over something else or which of the autogynephilic theories to prefer, so I just voted for everything that wasn't autogynephilic.
If there's an obvious flaw with this strategy, I'd love to know so that I don't repeat it.